Advanced transport telematics positioning requirements: An assessment of GPS performance in Greater London

This paper presents the results of a study carried out in the Greater Londo n area to assess and characterise the performance of the Global Positioning System (GPS) for vehicle positioning in urban areas. The performance asses sment addresses, in varying levels of detail, the issues of service coverag e, positioning accuracy, integrity and availability of service. The project was supported by Racal Survey Limited and is part of the wider research at Imperial College in the area of architectural design and testing of Advanc ed Transport Telematics (PITT) systems. The results highlight the shortcomi ngs of GPS as the sole means for in-car navigation in urban areas and detai ls the temporal and spatial considerations to be taken into account in the process of designing an integrated positioning system capable of meeting na vigation requirements placed on ATT systems.